Originated on the GameArena messageboards (www.gamearena.com.au) and was short for "Secret Language Of Women". It started off as a thread in which a widely distributed email containing satire of what women mean when they say certain phrases was posted.
The thread has spawned duplicates after each subsequent thread was locked and is today a haven for Telstra employees to converse as it's not blocked by their company firewall.

The thread titles of SLOW vary and usually involve a pun or something that incorporates the word "slow".

A relatively slow learner, who while struggling to keep up with everyday tasks, cultural evolution, or academics, is in a temporary (and usually domain limited) state of high reason, capable of demonstrating some set of the complex products of creativity and/or analytical thought. An effect due to some combination of factors such as intrinsic motivation, autistic spectrum disorders, emotional intelligence, mental specialization, and the powers of chance.

"But I thought Einstein couldn't speak till he was four".
"He was just slow"

A non-existant drug that is the opposite of speed, whose effects include: delayed reactions, randomly falling alseep, lack of motivation and or movement, and feeling as if you are living in slow motion.

A: Dude, I thought she was about to OD on slow, it took her 5 minutes to answer my yes or no question!

B: Shit man! That's bad! I need some slow, I've been way to productive lately.